Cylinder head gasket for internal combustion engines



CYLINDER HEAD GASKET FOR INTERNAL COMBUSTION'ENGINES Sept. 26, 1933. F. R. STEPHENS Filed April 2, 1932 ww nllihlltill leakage of'the cooling water into" the cylinders,

' Patented Sept. 26, 1933 l f 1328,116 I VVUNIITEDI sTAres P E T; Q Z

,l CYLINDERBEAD': GASKET FORIINTERNAL' COMBUSTION ENGINES" .7 Frederick .Roy Stephens, Oshawa, Ontario, Can ada, assignor to General Motors Corporation,

Detr oit,cMich., acorporation of Delaware invention relates to gaskets oillarge area such as are placed betweenthe upper end. of

multiple cylinder engine cylinder blocks and the under surface of the cylinderhead casting, which 5 is common to all the cylinders; the gaskets to which I refer being of the type whereinta sheet ture., Although no limited as regards use to engines having any particular number of cylinders six cylinder engines, andeight cylinder engines with the cylinders line, such asare used in present day automobiles, are mentioned as engines for use with which my improved gasket is especially designed; and the object of my invention is to provide agasket of such construction that the cylinder walls will not bedistortedlb'y the tightening of the bolts whereby the head is secured to the block, with the gasket between adjacent surfacesof the two parts'..=; fllli'here is as a mattero'f course no particular difficulty informing perfectly plane surfaces upon theiinder side of the head casting and the upper 5 end of vthe cylinder block; both of which are of large area, .of engines such as Ihavementioned; and if, the head could be secured to the block without an intervening gasketvtherewould be no distortion of the cylinder walls; practice, howand for other purposes; and I have foundthat when gaskets heretoforein use are used distortion secure the head casting to the cylinderblockwith the gasket between them; areproperly tightened. Such distortion tends toproduce binding of the pistons .in their cylinders and, if the pistonsare flttedfloose enough to avoid binding 'then they are apt to be noisy and thejen'gine to' have, objec; tionable piston knock,as the'noise is commonly called. "l The reason why distortionis produced asthe holding bolts, are tightened andthe parts adapt themselves to oneanother is that different parts of the gasket are, compressed to different degrees during such tightening, with the result that the thickness of the gasket of the form'inuse at the present time varies at difierent points in the area thereof. along theperiphery where the yieldable asbestos or' like materiallayer iscomparatively free to expand tightening of the, bolts 'will produce the greatest reduction in thickness of the gasket, while further in toward the middle parts where the yieldable mater ial is more con-1 6f the'cylinder walls occurs-whenthe-boltswhich For the holding bolts, and time distortion-which resisting reductionin thickness of the gasket at-J certain definite places'as'thebolts are tightened; j t Y Even were it possible to subject every h'olding' bolt to precisely the same tension the thickness of the t gasketwould varyappreciably throughout the areas 7 V- of contact between'the enginelpartsand the two surfaces thereof and in actualjpractice wherein the tension to which the holding bolts. are fsubjected cannot be definitfilydetermined; and inifact varies throughout a considerable range, the thick ness to which'the gasket is reducedfduring't'the' securing of the headin placehas beenifoundto vary tofa considerable extent throughout its area. The material of both the head casting and the cylinder block is elastic andyieldsnas" the bolts are tightened and the surfaces of the blockand head faccommodate themselves to variationsin thickness of the gasket;v but thestructure 0f the block isfsuch that ityields' 'more than the comparatively rigid head; from whichlit follows that ,the block rather than the head is distortediduring the tightening of the Qholdingfbolt's, which; distortion results in distortion of the cylinderwallsf I as above explained. f y The'distortion herein ;menti0ned-;.is due to v theheadcasting, to featuresxinherent in such) gasket's as have been available gandini use prior not due to temperature-of thefiblock or head.

The temperatures 'attained'by the engine whenin, v

operationno doubt produces a certain amount of redistribution'off stresses due to the tightening follows the securing of the head in place; but in the development of'myinventionl have found that the -disftortlior referred'to is-produced even in a cold'engine when gaskets stems have been heretofore obtainable'are used; whereas on the contrary when aga'sket' in accordancewith my invention is usedthere is no appreciable distortionwhen theiengineis cold, andno piston knock in a heated condition,

when the engine-is i o m pn n thwart??? no structural fatures of the cylinder block fand of 9.0

. 1,928,116 During such tightening the more flexible cylinder block has obviously to adapt itself to the comparatively rigid head and to variations in thickness of the gasket, thus producing distortion of the cylinder walls as explained. V 1

The above as a matter of course applies to gas kets as heretofore made wherein the side thereof has not been thickened as by the hem 22 or shim member 23 ,or its equivalent, and wherein variations in thickness of the gasket as the bolts are tightened resultsin distortion along the party 26 of the block and in the cylinder walls. When, however, as in my invention, the gasket is made thicker along the side thereof adjacent the part 26 of the block tightening of the holding bolts does not reduce the thickness of the gasket in that region as much as when the thickened fea-,

The proper thickness and width for the hem I v orshim varies somewhat injgaskets forjdifierent engines, being dependent uponthe structure and arrangement ofv the engine parts. The particular gasket illustrated and hereinbefore described is one which was designed for, and which has been used with manystraight eight engines used in Buick automobiles, and has proven successful der walls has ,been obviated. I Having thusdescribed and explained my invention I claim anddesire to secure by Letters Patent: a

1. A gasket comprising a'layer of compressible gasket material having a metal layer thereon,

said metal layer being folded upon itself to form i for the purpose hereinbeforeexplained for which I y it was designed in that distortion of the cylinan. integral hem lying snugly on one side thereof 1 and extending along oneedgeof the gasket.

- e 2. A gasket comprising a layer' of compressible gasket material, a bottom metal layer and a top 1 metal layer, one of said metal layers having aninv tegral hem bent inwardly to lie snugly againstthe 'in'ner'side thereof and against the compressible layer'and extending along one edge of the gasket.

REDERIC ROY STEPHENS. 

